Turbomachinery transfers energy between a rotor and a fluid. In a turbomachine, like an axial compressor, the discharge pressure of the compressor will typically vary with the shaft speed. Ambient air, as a working fluid, enters an inlet of a compressor and rotation of the compressor blades compresses the working fluid. As the compressor speed slows down, the discharge pressure of that compressor generally will go down. Likewise, as the compressor speeds up, the discharge pressure increases.